<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>websocket</title>
</head>
<body>
<script>
     let socket = new WebSocket('ws://localhost:9999');
     socket.onopen = function(){
        console.log('1. 客户端连接上了服务器');
        socket.send('hello');
     }

     socket.onmessage = function(event){
        console.log(event.data);
     }
</script>
</body>
</html>